Factored Correlator Model: A Solution for Fast, Flexible, and Realistic GNSS Receiver Simulations

Joao S. Silva, Pedro F. Silva, Antonio Fernandez, Jose Diez, and Jose F.M. Lorga

Abstract:	An analytical model for the outputs of a GNSS receiver’s correlators is presented in this paper, the Factored Correlator Model (FCM), as well as validation results (obtained using statistical models and the GRANADA Bit-True software receiver simulator). The FCM separates the effects of carrier and code Doppler and misalignment on a GNSS receiver's correlator outputs into several multiplicative factors and allows the inclusion (or not) of each factor independently. Since it is an analytical model, the computation rate can be as low as the tracking loop rate, dramatically increasing simulation speed. In short, the FCM significantly increases simulation speed while still accounting for correlation losses due to numerous effects, providing a swift, flexible, and realistic way to test different architectures, either of standalone GNSS receivers (for GPS, Galileo or other systems) or multi-system solutions. The FCM has been implemented in MATLAB® and integrated in a Simulink® blockset, which is now included in the GRANADA product family. An example of an implementation of an aided multi-channel GNSS receiver's tracking loops (using the FCM Blockset) is also included in this paper.
Published in:	Proceedings of the 20th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2007) September 25 - 28, 2007 Fort Worth Convention Center Fort Worth, TX
Pages:	2676 - 2686
Cite this article:	Silva, Joao S., Silva, Pedro F., Fernandez, Antonio, Diez, Jose, Lorga, Jose F.M., "Factored Correlator Model: A Solution for Fast, Flexible, and Realistic GNSS Receiver Simulations," Proceedings of the 20th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2007), Fort Worth, TX, September 2007, pp. 2676-2686.
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